3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
The influence of extraction temperature on CIE L * , a * , b *
colour characteristics or on pH values was only negligible.
S t a t i s t i c a l E v a l u a t i o n
All the above mentioned characteristics were used for
the classification and mutual recognition of both wine grape
varieties using the principal component analysis (Fig. 3.) and
canonical discrimination analysis 22 .
Both statistical approaches provided practically 100%
correct classification of both varieties. As also follows from
discriminant analysis, all the monitored characteristics are
dependent on the mass of grape skins used for respective extract
preparation.
Additional experiments are in progress to evaluate the
influence of solvent on the above-mentioned characteristics
as well as to analyze the profile of polyphenols in both grape
skin varieties.
Conclusions
Multi-experimental analysis performed with methanolic
extracts prepared from grape skins of two varieties (St. Laurent
and Alibernet) by PFE, revealed their significant antioxidant
and radical-scavenging abilities, in significantly positive
correlation with the TPC content. The influence of extraction
temperature on radical – scavenging abilities, tristimulus values
or TPC content is non-significant.
Czech Science Foundation (Project No. GA203/08/1536),
Academy of Sciences of the Czech Republic (Institutional
Research Plan No. AV0Z40310501) and Science and Research
Assistant Agency (Project APVV SK – CZ 0072 – 07) are
gratefully acknowledged for the financial support. Authors
would like to express their thanks to Dr. Milan Suhaj (Food
Research Institute, Bratislava) for statistical evaluation of
experimental data and visualisations.
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